Process of reclaiming rubber.



'1 STATES-PATENT omer.

Reamer w. Even-En, or AKRON, omanssrenon r THE rmEsroNE manaitem maCOMPANY, OF AKRON, Q HIO, A CORPORATION OF OHIO.

. rnocnss or n'rjcrnmme- RUBBER.

To all'whom t'tmay concern: p

Be it known that I, HERBERT W. KUGLnR, a citizen of the United States,residing at -Akron, Summit county, State of Ohio, have invented certainnew and useful Improvements in Processes of Reclaiming Rubber, ofwhichthe following is a specification.

My invention relates to reclaimings waste ,yulcanized rubber and has forits principal object obtaining rubber from such waste in. such a manneras to restore it largely to its Inciden original unvulcanized condition.tally, my process is usually accompanied by waste, such as fibers.

A large commercial use for my process :1s found in the reclaiming ofwaste rubber corrtaining a percentage of fabric, sulfur, and

' inert ingredients, -for example, worn vehicle tires.

*Theeulfur in vulcanized rubber exists in bath the free and combinedstates. The

usual treatment of waste rubber while adeguate for the removal offabric, removes only a portion of the free sulfurand does not removeanylof the combined sulfur. It actually increases the amount of combinedsulfur because at the temperatures usually employed a portion or all ofthe uncombined sulfur may go into combination with the rubber.

The so-called reclaimed rubbers of commerce consist of a mass of more orless finely divided particles of vulcanized rubber which cohere byreason of the softening effect of heat, or due to the presence of oilsor other ingredients in the mass. As distinguished from the generallyuse methods my improved process contemplates the elimination of not onlyfree sulfur but also a considerable proportion of combined sulfur fromthe rubber, with the result that my product is substantially in thecondition of the rubber or rubber compound before vulcanization.

The differences between the result of my processand the products of theprior art may be'shown by the application of a simple test. Thus, if anyof the so-called reclaimed rubbers of commerce produced by the usualmethods is treated with a rubber solvent without the application of heator .pressure, it swells to several times its original volume by-,absorption of the solvent,

Specification of Letters Patent.

Patented Jan. 12, 1915:.

Application filed December 20, 1912. Serial No. 737,819.

solution made from a similar unvulcanized rubber compound.

In carrying out inyiprocess I make'si m'ultaneously use of preferably amember of the carbocyclic amido compounds, say-anilin, toluidin orxylidin, and a substance capable of absorbing or combining with sulfuras for example the hydrates of the alkali metals. term adjuvant agentImean a supstance the presence of; which permits the eaction to takeplace but which itself at the end of the reaction is unaltered, suchagent heretofore having been frequently characterized as a catalyzer or;catalytic agent. The proportion of the adjuvant agent used w1ll varywith the nature of the scrap. The usual proportions which I have ployedare from 2 to 5 of anilin. The amount of the substance capable ofabsorbing or combining with sulfur is determined primarily by theamountof sulfur inthe scrap used and is also dependent upon whether itis used--for the additional purpose of removing fabric or otheringredients from the rubber.

agent and the sulfur absorbing substance and the requisite amount ofwater to insure the even distribution of the different mate rialsthroughout the mass. The heater is an adjuvant agent;

successfully em-g per centum in weight then closed and the temperatureraised to correspond to a steam pressure of .from to .150 pounds,although in practice a tempera ture corresponding to 100. pounds steampressure will befound most suitable for the f average run of scrap. Thistemperature is maintained for a period of say eight hours, or for ashorter or longer period, de ending upon the nature of the scrap, the claracter and quantity of the adjuvant agent, temperature, pressure andthe physical condition of the finished product it is desired to obtain.At the end of the treatment the heater or digester is emptied and therubber washed with water until free from water soluble substances. Itcan then be dried and sheeted by any of the well known methods.

Vulcanized rubber has certain physical characteristics which render itsreclamation necessary before it can be used industrially to any extentin lieu of crude rubber. It is impossible to reduce the rubber to aplastic mass by mechanical agitationso that it can be formed intodifferent shapes and have incorporated with it fabric, sulfur, and othermaterials and be vulcanized into new articles. Another characteristic ofvulcanized rubber as explained in a previous paragraph is its inabilityto form true solution with a rubber solvent and so asto give rub ments.

When vulcanized rubber is subjected to treatment according to my processthe resultant product is capable of being reduced to a plastic mass thatcan be worked into sheets and other forms and on mixing with sulfur andother ingredients can be vulcanized and handled like new rubber. It willalso give with rubber solvents true solutions such as those made fromsimilar compounds that have not been subjected to vulcanization. i

The chemical reactions that take place during the operation of myprocess cannot be definitely or entirely stated but appear to come underthe head of those heretofore commonly known as catalytic reactions, theamido substance acting as an adjuvant agent to carry the sulfur from therubber to the .sulfur absorbing substance present. In the claims I havestated this action but I desire it to be understood that such statementis intended to be descriptive rather than de- 0 finitive.

I am aware that it has been heretofore.

proposed to use substances of the amido group (specifically anilin,toluidin or xylidin), for the reclaiming of vulcanized rub- 5 ber but ina different way and with a different object in view. For example, it hasbeen proposed to use an amido substance as a solvent for vulcanizedrubber. In such processes a large amount of the amido substance, manytimes the weight of the scrap, *is used, and the mixture is heated untilthe 4 rubber is depolymerized to such an extent that the depolymerizedproductsdissolve in the amido substance. These depolymerized productsare no longer rubber. It is then treated with a substance capable ofthrowing the rubber out of solution, such as an alcohol or an acid. Thisprocess does not effect the elimination of sulfur but rather increasesthe amount of combined sulfur, as heretofore stated, and the so-calledreclaimed rubber produced by it resembles that produced by subjectingvulcanized rubber to high temperatures or to the action of othersolvents at high temperatures. It has also ber cebeen proposed to heatvulcanized rubber with much smaller. amounts of an amido substance, say10 to 20 per centum, with the object of effecting a chemical combinationbetween the rubber and the amido substance and thus produce a newcompound to be used to replace'crude rubber. This compound contains allthe sulfur that originally existed in the free and combined states inthe vulcanized rubber used.

My process is distinguished from those aboveoutl-ined and from allothers known to me, by the important fact that I use the amido substancein small proportions and in conjunction with a substance capable of abwsorbing or combining with sulfur and obtain thereby a product that issubstantially the same as the unvulcanized compound from which the"vulcanized rubber was made. That is to say, my product is not a comgmpound of the amido substance and rubber, nor is it the result ofsolution in the amido compound, nor does it contain any new or differentingredient than was in the original rubber compound, w ile the whole ofthe free sulfur, and to a great extent the combined sulfur, has beeneliminated.

I claim:

1. The process of reclaiming rubber which consists in simultaneouslytreating vulcanized rubber under suitable conditions of temperature andpressure with an agent such as anilin, t'oluidin, xylidin or the likeand a substance capable of combining with or absorbing sulfur,substantially as described.

2. The, process of reclaiming rubber, which consists in simultaneouslytreating vulcanized rubber under suitable conditions of temperature andpressure with an adjuvant agent and a substance capable ofcombining'with or absorbing sulfur, substantially as described.

3. The process of reclaiming rubber, which consists in simultaneouslytreating I vulcanized rubber under suitable conditions of temperatureand pressure with a carbocyclic amido compound such as anilin, toluidin,xylidin, or the'like, and a caustic alkali solution, substantially asdescribed.

4. The process of reclaiming rubber, which consists in simultaneouslytreating vulcanized rubber under suitable conditions of temperature andpressure with a carbocyclic amido compound such as anilin, toluidin,xylidin, or the like, and a caustic alkali solution, and washing therubber, substantially as described.

5. The process of reclaiming vulcanized rubber which consists insimultaneously treating the material in a finely divided cond1t 1on andunder heat and pressure with an ad uvant agent and a substance capableof combining with or absorbing sulfur.

6. The process of reclaiming rubber which p greases consists insimultaneously treating vulcanized rubber under suitable cond tions oftemperature and pressure with an 'adjuvant agent and a substance capableof combining with or absorbing combined sulfur of the vulcanized rubberonl in the presence the vulcanized rubber, substantiallyv as de-'scribed.

8. The process of reclaiming vulcanized rubber containing textile fabricwhich consists in simultaneously treating thematerial in a finelydivided condition under suitable conditions of temperature and pressurewith a substance capable of destroying the fabric, and an ad uvant agentthe presence of which causes such substance to combine with or absorbthe combined sulfur of the vulcanized rubber, and mechanicallyseparating the reclaimed rubber from the residue, substantially asdescribed.

9. The process of reclaiming vulcanized rubber containing textile fabricwhich consists in simultaneously treating the material in a finelydivided condition under suitable conditions of temperature and pressurewith a caustic alkali solution capable of destroying the fabric, and acarbocyclic amido compound adj uvant agent the presence of which.

causes such caustlc alkali to combine with or absorb combined sulfur ofthe vulcanized rubber, substantially as described.

10. The process of reclaiming vulcanized rubber containing textilefabric which consists in simultaneously destroying the fabric andtreating the vulcanized rubber under suitable conditions of temperatureand pressure with an adjuvant agent and a substance capable of combiningwith or absorbing combined sulfur of the vulcanized rubber only when inthe presence of an adjuvant agent, substantially as described HERBERT W.Keenan.

Witnesses:

MARY E, CAHOON, R. D. Lm'rnn.

